include/basebmp/stridedarrayiterator.hxx

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  19
  20 #ifndef INCLUDED_BASEBMP_STRIDEDARRAYITERATOR_HXX
  21 #define INCLUDED_BASEBMP_STRIDEDARRAYITERATOR_HXX
  22
  23 #include <basebmp/metafunctions.hxx>
  24
  25 namespace basebmp
  26 {
  27
  28 /** Like vigra::StridedArrayIterator
  29
  30     Changed semantics re. DirectionSelector<StridedArrayTag>: stride
  31     now counts in <em>raw</em> bytes
  32
  33     Adapts given ptr, in a way that iterator increments move forward
  34     in strided steps. Stride can, by the way, also be negative
  35  */
  36 template< typename T > class StridedArrayIterator
  37 {
  38 public:
  39     typedef typename clone_const<T, unsigned char>::type  internal_type;
  40
  41     /** Create iterator
  42
  43         @param stride
  44
  45         Stride in bytes. Given value should better match memory layout
  46         of T, as memory gets reinterpret-casted.
  47      */
  48     explicit StridedArrayIterator(int stride, T* ptr = 0) :
  49         stride_(stride),
  50         current_(reinterpret_cast<internal_type*>(ptr))
  51     {}
  52
  53     /** Copy from other StridedArrayIterator, plus given offset
  54
  55         @param offset
  56         Offset in bytes
  57      */
  58     StridedArrayIterator( StridedArrayIterator const& rSrc,
  59                           int                         offset ) :
  60         stride_(rSrc.stride_),
  61         current_(reinterpret_cast<internal_type*>(
  62                      reinterpret_cast<T*>(rSrc.current_)+offset))
  63     {}
  64
  65     void operator++()       {current_ += stride_; }
  66     void operator++(int)    {current_ += stride_; }
  67     void operator--()       {current_ -= stride_; }
  68     void operator--(int)    {current_ -= stride_; }
  69     void operator+=(int dy) {current_ += dy*stride_; }
  70     void operator-=(int dy) {current_ -= dy*stride_; }
  71
  72     int operator-(StridedArrayIterator const & rhs) const
  73     { return (current_ - rhs.current_) / stride_; }
  74
  75     bool operator==(StridedArrayIterator const & rhs) const
  76     { return current_ == rhs.current_; }
  77
  78     bool operator!=(StridedArrayIterator const & rhs) const
  79     { return current_ != rhs.current_; }
  80
  81     bool operator<(StridedArrayIterator const & rhs) const
  82     { return *this - rhs < 0; }
  83
  84     bool operator<=(StridedArrayIterator const & rhs) const
  85     { return *this - rhs <= 0; }
  86
  87     bool operator>(StridedArrayIterator const & rhs) const
  88     { return *this - rhs > 0; }
  89
  90     bool operator>=(StridedArrayIterator const & rhs) const
  91     { return *this - rhs >= 0; }
  92
  93     T* operator()() const
  94     { return reinterpret_cast<T*>(current_); }
  95
  96     T* operator()(int d) const
  97     { return reinterpret_cast<T*>(current_ + d*stride_); }
  98
  99 private:
 100     int            stride_;
 101     internal_type* current_;
 102 };
 103
 104 } // namespace basebmp
 105
 106 #endif /* INCLUDED_BASEBMP_STRIDEDARRAYITERATOR_HXX */
 107
 108 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */